1. Field of the Invention
The present invention relates to scroll machines, and in particular, to the manner in which a working fluid is drawn into the variable volume working pockets which are defined between the fixed and orbiting scrolls of a scroll compressor.
2. Description of the Related Art
Referring to FIG. 1, a scroll compressor 10 is shown, which includes main housing 12, bottom cap 14 with base 16 secured to the lower end of housing 12, and a separator plate 18 and top cap 20 each secured to the upper end of housing 12 by a welding, brazing, or other suitable operation to define an enclosed hermetic housing in which the motor-compressor unit 22 of compressor 10 is disposed. Motor-compressor unit 22 generally includes a first, fixed scroll 24, a second, orbiting scroll 26, crankcase 28, drive shaft 30, stator 32, rotor 34, and outboard bearing assembly 36. Separator plate 18 is secured around its perimeter to the interior of housing 12, such as by welding, and divides the interior of the housing 12 into a suction chamber 38 in fluid communication with suction port 40 in housing 12, and discharge chamber 42 in fluid communication with discharge port 44 in top cap 20.
Fixed scroll 24 is secured to separator plate 18, such as by a plurality of bolts, and includes outer wall 46 extending from base plate 48, and an involute wrap 50 extending from base plate 48 and disposed inwardly of outer wall 46. Fixed scroll 24 further includes a plurality of mount flanges 52 spaced radially about the end of outer wall 46 opposite base plate 48, and a plurality of bolts secure mount flanges 52 to crankcase 28. Crankcase 28 includes main bearing 54 in which the upper portion of drive shaft 30 is rotatably supported. Stator 32 is fixed within housing 12 by a plurality of bolts (not shown) which pass through outboard bearing assembly 36, stator 32, and into crankcase 28. Drive shaft 30 is secured to rotor 34 in a suitable manner, and outboard bearing assembly 36 includes outboard bearing 56 which supports a lower end of drive shaft 30. The upper portion of drive shaft 30 includes an eccentric end mounted within annular hub 58 extending downwardly from base plate 60 of orbiting scroll 26. Orbiting scroll 26 additionally includes an involute wrap 62 extending upwardly from base plate 60 thereof, which is in meshing relationship with wrap 50 of fixed scroll 24. Oldham coupling 64 is operatively coupled between orbiting scroll 26 and crankcase 28 to prevent rotation of orbiting scroll 24, as is known.
In operation, electrical energization of stator 32 rotatably drives rotor 34 and drive shaft 30 to move orbiting scroll 26 in an orbiting manner with respect to fixed scroll 24. A working fluid at suction pressure is drawn from suction chamber 38 into a suction inlet 66 of fixed scroll 24, and is compressed within the plurality of variable volume, working pockets which are defined between wraps 50 and 62 of fixed and orbiting scrolls 24 and 26, respectively, as orbiting scroll 26 rotates in a known manner. The compressed working fluid is then discharged through discharge outlet 68 in base plate 48 of fixed scroll 24, through discharge check valve assembly 70, and into discharge chamber 42 at a discharge pressure.
More specifically, working fluid at suction pressure enters suction chamber 38 via suction port 40 and initially impinges upon crankcase 28. Thereafter, a portion of the working fluid flows downwardly within suction chamber 38, as designated by arrow A in FIG. 1, and another portion of the working fluid flows upwardly within suction chamber 38, as designated by arrow B in FIG. 1. Problematically, the portion of the working fluid which flows upwardly within suction chamber 38 along arrow B contacts housing 12, separator plate 18, and outer wall 46 of fixed scroll, which tends induces a spiraling, turbulent flow of the working fluid in the upper portion of suction chamber 38, illustrated by arrows C in FIG. 1, before the working fluid is eventually drawn into suction inlet 66 of fixed scroll 24.
The turbulent flow of the working fluid within the upper portion of suction chamber 38 can potentially adversely effect the operating efficiency of compressor 10 by inhibiting uniform suction of working fluid into the suction inlet of the scrolls. Additionally, the working fluid also tends to become heated, for example by the discharge gas above separator plate 18, if the working fluid circulates within the upper portion of the suction chamber before entering the suction inlet of the scrolls, which can also reduce the efficiency of the compressor.
It is known to mount a baffle in a scroll compressor to the inner surface of the compressor housing over the suction inlet port. Problematically, however, these types of baffles are difficult to assemble after the motor compressor unit is installed within the compressor housing, and alternatively, when these types of baffles are attached to the interior of the compressor housing prior to installation of the motor compressor unit, same can impede mounting of the motor compressor unit within the compressor housing. Also, the connection between the baffle and the compressor housing may not be substantially rigid, and suction gas may be allowed to escape into the suction chamber as same travels between the suction baffle and the inlet of the scrolls.
What is needed is a scroll compressor which is an improvement over the foregoing.